The learning process in schools still experiences several problems, including in helping students to have critical thinking skills. Critical thinking skills can be optimized with the development of learning resources. This research aims to develop learning resources in the form of problem-based teaching materials. The research method uses R&D (Research and Development) with a qualitative descriptive approach. Research data collection instruments in the form of interview sheets for teacher needs analysis and student needs analysis questionnaires, as well as students' critical thinking skills. The results of the needs analysis of 60 grade XI science students found that 66.7% had a handbook for learning biology, but 96.7% only had a handbook in the form of daily material, the majority of which were difficult for students to understand. So according to 78.3% of students the handbook used is inadequate as a learning resource, 86.6% of students need other learning resources to support learning activities, and 86.7% of students need other learning resources that can be understood independently. The results of the critical thinking test analysis of 50 grade XI science students were obtained 15.73%, which is included in the very low category. These results show the need to develop teaching materials in the form of problem-based digestive system interactive Emodules.